Al-Qasas 28:53

Wa-itha yutla AAalayhim qalooamanna bihi innahu alhaqqu min rabbinainna kunna min qablihi muslimeen

And when it is recited to them, they say, "We have believed in it; indeed, it is the truth from our Lord. Indeed we were, [even] before it, Muslims [i.e., submitting to Allāh]."

And when this (Qur’ān) is recited to them, they say, “We believe in it. It is the truth from our Lord, and we are the ones who had submitted (to it) even before it (was revealed).”